From the viewpoints of improving installation space efficiency, transporting workpieces to adjacent machine tools, and operability of an operator, in a machine tool, it is preferable for the occupied area to be small, and in particular, it is desirable for the width as viewed from the front to be small. For the purpose of making the occupied area small in this manner, for example, in Patent Document 1, a machine tool is proposed in which two spindle units are disposed on a column that is movable forward and backward in a horizontal direction, the spindle units being capable of moving up and down and horizontally. The machine tool of Patent Document 1 is favorable in terms of lowering costs and conserving space.
Further, in Patent Document 2, a numerically controlled NC lathe is proposed in which, by means of a structure in which a spindle is oriented vertically, space is conserved and the equipment number per unit area is increased, thereby enhancing productivity.
Incidentally, with the machine tools disclosed in Reference Document 1 and Reference Document 2, the structure is complex because a biaxial slide mechanism, which is perpendicularly arranged as viewed from the front, is provided. Moreover, because a heavy slide member is moved, in order to obtain sufficient stability, a base portion must be provided and affixed, such that the overall weight of the apparatus becomes quite heavy.
Looked at from this standpoint, in Patent Document 3, an arm is provided that rotates within a vertical plane with respect to a horizontally directed slide mechanism. According to this type of machine tool, a single axis is sufficient for the slide mechanism as view from the front, thus advantageously enabling a simple structure.    Patent Document 1: Japanese Patent No. 3278135    Patent Document 2: Japanese Laid-Open Patent Publication No. 2003-266203    Patent Document 3: Japanese Patent Publication No. 05-002446    Patent Document 4: Japanese Laid-Open Patent Publication No. 2004-314203    Patent Document 5: Japanese Laid-Open Utility Model Publication No. 63-063757    Patent Document 6: Japanese Laid-Open Patent Publication No. 55-112753    Patent Document 7: Japanese Laid-Open Patent Publication No. 07-251333
Although the machine tool disclosed in the aforementioned Patent Document 3 has a simple construction, the machine tool includes a biaxial slide mechanism (X table and Z table) that intersects on the horizontal plane, and the area occupied thereby is not small by any means. Further, as viewed from the front, because an X-axis direction slide mechanism is provided, the width of the machine tool also is not small in scale.
Furthermore, due to the fact that a unit including a processing spindle slides horizontally in the X direction, a moment force is generated with respect to the floor, which tends to shake the equipment laterally about a support point. The unit that includes the processing spindle is comparatively heavy, and therefore the moment is large as well, so that in order to obtain sufficient stability, the base portion must be substantially affixed in place, such that the overall weight of the structure increases. Furthermore, similar to the example disclosed in Patent Document 2, the base must be set in an overhanging or jutting manner, and in the case that plural machine tools are arrayed laterally, the line length thereof increases.
When a mechanism is adopted, in which the horizontal X-direction slide mechanism of the machine tool in Patent Document 3 is rotated by 90° so as to become vertically oriented, the width of the machine as viewed frontally becomes quite small.
Further, with the configuration of Patent Document 3, even if the machine width is made smaller, because the length of the rotation arm is not changed, in the case that a plurality of machine tools are arranged adjacent to one another, the machine tools must be positioned while being separated sufficiently so that the rotation arms thereof do not interfere mutually with each other, thus presenting another obstacle to further improving space efficiency.
Further, with the structure of Patent Document 3, even though the width of the machine tool and the installation area thereof may be small, transporting of workpieces between each of the machine tools is not automated, and moreover, even if such an automated system were provided, with a slow transport mechanism, the processing time becomes longer as a result, and efficiency is poor.
In addition, when the workpiece transport mechanism is provided separately from the mechanism that fixes the workpiece and processing is performed thereon, delivery of workpieces between both of these mechanisms is required, so that the mechanisms and processing sequence becomes complex. Still further, with such a complicated mechanism, the overall scale is increased, so that the point of making the machine tool itself smaller in scale is overlooked.
Further, with the machine tool, processing is performed while attaching and detaching a plurality of tools with respect to the workpiece, and it is preferable to store multiple tools, which are capable of responding to various types of workpieces. However, when the occupied area by the machine tool is small, the space for storing such multiple tools vanishes as well.
When a mechanism is provided in addition with respect to the machine tool for storing multiple tools, the area occupied by the machine tool becomes enlarged, and efforts to make the machine tool itself smaller in scale are ignored.
When a mechanism is adopted as described above, in which the horizontal X-direction slide mechanism of the machine tool in Patent Document 3 is rotated by 90° so as to become vertically oriented, since the machine tool assumes a shape of being longer than it is wide, if a mechanism were added for storing tools, the slider is brought into an imbalance state and worsened by generation of vibrations and the like, and processing precision tends to be lowered.
Furthermore, in the case that a mechanism for storing multiple tools is provided, a burden is placed on the operator to confirm that all of the tools are normal and proper, and before processing is carried out, it would be preferable to provide an automated type of confirmation.
Further, in a machine tool for manufacturing engine components, for example, it is desirable to provide a machine tool that is effectively small in scale, which conserves space, and which facilitates reductions in cost.
In a machine tool of this type, in Patent Document 1, in relation to a processing apparatus for processing valve holes in a cylinder head making up an engine, the applicant of the present invention has proposed a configuration for carrying out a process to incline a rotating unit, on which a cylinder that forms the workpiece is mounted, at a predetermined angle. According to this processing apparatus, it is possible to reduce the apparatus size and simplify the apparatus overall, while conserving space and reducing the cost thereof.
In Patent Document 4, a machine tool is disclosed which includes, in place of the aforementioned rotating unit, a rotation table apparatus having a circular shaped rotation table that rotates on a horizontal surface, wherein a spindle is provided on the rotation table, the spindle being affixed to and rotatably supported by the inner ring of a roller bearing.
Incidentally, in the cylinder block, cylinder head, etc., in the aforementioned engine components, various forms and models are provided. According to the differences in these types, for example, such as straight and V-type, or 4-cylinder and 6-cylinder types, there are a large number of parts having different shapes.
Consequently, with the aforementioned conventional configuration, two or more reference holes for positioning are provided in the workpiece, and positioning of the workpiece is performed by providing pins, which correspond to the reference holes, on a pallet which makes up a mounting base on which the workpiece is mounted. The pallet with the positioned workpiece loaded thereon is fixed onto a table of the machine tool.
Notwithstanding, because a large number of workpiece shapes exist as described above, a large number of pallets corresponding to the various shapes of the workpieces must be prepared, and thus the manufacturing cost for the table, as well as the storage location therefor, etc., tends to cause problems.
Further, in terms of the aforementioned positioning pins, in Reference Document 3, movable type pins are disclosed, along with a pin positioning device, corresponding to each respective type of workpiece shape.
However, with the pin positioning device disclosed in the aforementioned Patent Document 5, because the workpiece, which is the object to be positioned, is a printed wiring board to be inspected, it cannot be assumed that a large load (e.g., a radial load or the like), such as the cutting resistance that is incurred during processing by a machine tool, would be imposed on the positioning pins and the moving elements therefor.
Furthermore, in the case of a machine tool that carries out machining on the aforementioned engine components, because machining chips (cutting chips) of the workpieces are generated, which could cause problems in the seals of the aforesaid moving elements, it would be difficult to divert use of the aforementioned positioning pin apparatus for the purpose of positioning workpieces for a machine tool.
With the aforementioned conventional machine tool, two or more positioning reference holes are provided in the workpiece, and positioning of workpieces is carried out by providing pins corresponding to the reference holes in a pallet, which makes up a mounting base on which the workpiece is mounted, and the pallet with the positioned workpiece loaded thereon is structured so as to be fixed onto a table of the machine tool.
However, because the shapes of the workpieces are large in number, a plurality of different pallets must be prepared corresponding to the shapes of the respective workpieces. Thus, manufacturing costs for the table, as well as the storage location therefor, etc., tends to cause problems.
Further, for these types of positioning pins, in Reference Document 5, movable pins are disclosed, along with a pin positioning device corresponding to each respective type of workpiece shape. However, with such a pin positioning device, because the workpiece, which is the object to be positioned, is a printed wiring board to be inspected, use thereof with a machine tool cannot be envisioned. Furthermore, in this pin positioning device, a structure is provided for positioning the printed wiring board with two pins by an urging force of a coil spring. More specifically, a structure is provided for positioning the printed wiring board while the pins are moved and retained at predetermined positions, and thus, positioning of the workpiece is not carried out precisely, and automatization thereof is difficult.
On the other hand, with the table that serves as a supporting body in the machine tool, lightness in weight and a small scale structure therefor are desirable. In Patent Document 6, a numerically controlled machine tool is disclosed, in which a pallet transport tool is operated by means of a moving unit equipped with a spindle, and from a pallet supporting base on which the pallet that positions the workpiece is disposed, the pallet is transported inwardly and outwardly on a horizontally displaceable table.
However, with the machine tool disclosed in the aforementioned Patent Document 6, a pallet that positions the workpiece and a pallet supporting base are used, and moreover, the machine tool is constituted by a structure in which the pallet is transported inwardly and outwardly on the table. Because a pallet supporting base and a table displacing mechanism, etc., are required, it is difficult for the table as well as other devices in the periphery around the table to be made small in scale.
Further, in general, when a machined object, for example, an engine component such as a cylinder block, cylinder head, etc., is processed by the machine tool, such processing is carried out under a condition in which the machined object has been positioned at a desired location.
In a case such as this, for example, together with providing two reference holes for positioning, in the machined object, by providing positioning pins (reference members), which correspond to the reference holes, on a pallet that forms a mounting base for the machined object, the machined object is properly positioned in a desired position. In addition, the pallet on which the machined object has been positioned and mounted is affixed to a table of the machine tool and processing is carried out thereon.
Consequently, in Patent Document 7, in relation to a table for positioning a printed substrate that forms a workpiece, a technical concept is disclosed in which two moving tables on which two edge portions of the printed substrate are fixedly mounted and which are movable in the Y-axis direction, and a fixed pin and moving pin disposed between the two moving tables, are provided. In addition, the fixed pin is affixed on the surface of the table, and by structuring the moving pin so as to be movable in the X-axis direction, the pins are made to correspond with the two reference holes of the printed substrate that is mounted on the moving tables, whereby positioning is carried out.
However, with engine components of the type described above, the positions of the reference holes that are utilized for positioning differ depending on the shape of the components. Thus, the position of the reference hole of the workpiece, corresponding to the fixed pin on the workpiece positioning table according to the above conventional configuration, is not limited to a fixed position, and in particular, when processing is performed on the side surfaces of the workpiece, it would be difficult for the processing surface to face toward the front of the tool, and thus accurate and rapid processing is difficult to carry out.
Further, there are also cases in which the workpiece positioning table itself is necessarily used as a transporting pallet. For this purpose, it is desirable for the structure of the table to be simplified and for the table to be light in weight. However, with the table of the aforementioned conventional technique, a total of three moving means, i.e., two moving means for moving the two moving tables, and a moving means for moving the aforementioned moving pin, are included. Therefore, the structure of the table is complex and the weight thereof is large.